You need your audience to remember and believe your arguments. You want their emotions to work in your favor. How can you learn to persuade fact-finders more effectively? Psychologists have done the research for you.

Which is the better courtroom tactic: Present an exhaustive list of material facts and relevant legal authority to impress the jury with the power of your case, or submit a succinct, well-organized list of seven items? Principles derived from psychological research can answer this question and others—both for young lawyers who need to optimally present a case and experienced lawyers who already have practical knowledge of psychological principles but would like to know more about persuasion tactics.

Two experienced San Antonio attorneys, Jim Stewart and Michele Petty, help illustrate how these psychological principles work and how they can prove useful in law practice. For example, Stewart, who is a highly respected divorce attorney, explains that, "In a child custody case where you have a lot of neighbors and friends that know the family and know the problems and everything else, even though every one of them could tell you 15 or 20 things—good for her, bad for him or vice versa—I usually limit each witness to four or five points. [When working with] a jury, you can just overwhelm them with facts, so you've gotta' keep it very simple." Psychological research, in fact, confirms Stewart's belief that the shorter list will be better understood and remembered, while the exhaustive list will be forgotten, except, perhaps, for a few items at the beginning and the end. To win, lawyers need to present concise arguments the audience can remember.

This and other principles from psychological research can give anyone a head start on strategies that take experienced lawyers a lifetime to learn—such as how to make arguments memorable, how to change people's attitudes and how to protect an already favorable attitude from attack by opponents. Do you want to improve your chances of carrying the day for your clients? Here is an overview of seven psychological principles that you can use to become a more effective and persuasive lawyer.

1. Seven Is a Magical NumberPsychologists know that long lists simply will not be remembered. In a famous 1956 article, "The Magical Number Seven," psychologist George A. Miller observed that human short-term memory holds about seven items, plus or minus two. For example, when someone shouts a typical seven-digit phone number to you, you can remember it long enough to dial it—but to remember a long international phone number, most people need to write it down. Similarly, limiting your main points to around seven will help people remember them, at least in the short term.

The point is that the judge must be able to remember what you wrote after he or she finishes reading your brief, and the jury must be able to recall your arguments during deliberations, especially if note taking is not allowed. This means, for example, that in opening statements or closing arguments, the personal injury attorney should not detail every medical complaint, however trivial, that the client has. Instead, discussing the most serious seven or so complaints will be more effective in convincing the judge, the jury and your opponent that your client was badly injured.

But what if seven items will not cover the volume of information you must present? In the courtroom, you can increase the amount of information you wish the judge or jury to remember by organizing and bundling your longer list into approximately seven logical topics, which may in turn contain seven or so items each. So, for example, in a family law dispute, instead of presenting a laundry list of demands for marital property, you could divide the list into categories based on everyday experiences your judge or jury would know, such as children's items (which would include furniture, toys and clothes), investments (stocks, bonds and mutual funds) and vehicles (cars, trucks, boats, trailers and jet skis). In this way, you can increase the number of items the fact-finder will remember later.

Petty, an accomplished personal injury attorney in San Antonio, agrees that the succinct approach works best. She explains, "You can go off on too many tangents and defeat yourself. Don't be led off into side issues. Don't try to prove things you don't need to prove. I use visual exhibits and I try to highlight a few things so that they are reinforced by multiple senses. The jury wants to hear and see the same few themes several times."

2. What You Expect Biases What You PerceiveLegal disputes are riddled with ambiguous situations that amount to judgment calls about how events occurred, or what the proper identification of an item or person is. Decades ago, psychologist Robert Leeper showed that suggestions from an experimenter will influence how people perceive ambiguous information. Knowing this, lawyers may use a carefully worded opening statement to sway a fact-finder toward their client's point of view by helping the judge or jury resolve ambiguous or conflicting evidence in the client's favor.

Suppose, for example, that your careless adolescent client shot her friend in a toy store. You might begin your defense by pointing out that your client picked up the weapon, which actually belonged to the shopkeeper, from a shelf stocked with realistically designed toy guns. She then pointed it at her friend's feet and mischievously said, "Dance, or I'll shoot!" while squeezing the trigger. A jury could see how the accused teenager might have thought the gun was a toy. In addition, you might allow the jury to compare the toy guns and the real gun to emphasize how similar they are.

What you expect biases how you perceive people, too, not just situations and objects. For example, if the plaintiff's attorney wishes to characterize a college student defendant as a wanton party animal, he or she may stress that the student belongs to a notorious fraternity. On the other hand, the youth's attorney will likely emphasize the client's membership in Eagle Scouts. Likewise, to benefit from positive connotations, the lawyer for a female defendant who is the biggest drug dealer in four states will stress the fact that the client is a grandmother. Such strategies tie in with principles researched by psychologist J. Evans and others.

Stewart uses suggestion during voir dire to predispose jurors to expect lying by an opponent's witness. He says, "I will often ask the jurors individually, 'Do you think you can smell out when a person's telling the truth or lying?' And they're going to say 'yes' and then I'm going to say, 'Because in this case there's gonna' be some lying going on coming from that witness stand under oath, and that's part of your job and weighing the testimony is to smell it out.' [T]hey know I'm not talking about my client ... so they sit there and they're looking for a lie [by my opponent's witness] and that's very effective."

3. Inoculation Weakens Opposing ArgumentsPsychological "inoculation" works like a vaccination to prevent a sympathetic audience from being "infected" by the opposition's arguments. This is paradoxical because you might expect that a vigorous presentation of your arguments alone is most effective. But psychologists William McGuire and Demetrios Papageorgis discovered that also presenting a weakened form of your opposition's arguments stimulates your audience to think about defenses to those weakened arguments, much like creating antibodies. As a result, your audience becomes resistant to persuasion, and your opponent's message is blunted before he or she even begins, even if you don't anticipate precisely what the argument will be.

The basic rule with inoculation is to disclose your liabilities before your opponent does, so you can put your spin on them. For example, a veteran San Antonio divorce lawyer had an affable, but philandering, male divorce client who had recently overcome an addiction to painkillers. The opposition was ready to portray the husband-client as a ne'er-do-well playboy junkie. Before the opposition had a chance, the husband's lawyer admitted up front that his client had a drug problem, but also explained that there were mitigating circumstances. First, the drug was prescribed for back pain; second, the husband successfully completed a drug rehabilitation program; and third, the husband was no longer addicted. The husband, who was characterized as a good-guy cowboy who owned up to his mistakes, won over the jury and got custody of his children.

Petty says inoculation is effective but it must be applied with care. "You need to get [the negatives for your side] out so the jury will think you are not trying to hide something.... But don't dwell on the negative; move on to positive things. You can't win by being defensive."

4. Make Your Audience ThinkGetting your seven or so main points into your audience's short-term memory is a start—but those points have to stick to do any good. As everyone knows, unimportant information, like yesterday's grocery list, fades fast. One way to improve remembering is to get your audience to think in a meaningful way about your issues—a tactic that is particularly appropriate in opening and closing arguments.

Asking your audience to think and relate your message to their own experiences aids memory. For example, when discussing why your client should be awarded a car out of marital property, you might ask members of the audience to think about how they use their cars every day and how important it is to them for getting to work or transporting the kids to school activities.

When speaking to a jury during voir dire, Stewart encourages his listeners to think deeply about his message by explaining how important jurors are to our system of justice, and asking the jurors to listen carefully so they may judge the credibility of witnesses and assess the evidence. This is one way that lawyers can help their audiences do what psychologists such as Fergus Craik and Robert Lockhart call "deep processing and elaboration," both mechanisms that make ideas easier to recall later.

5. Make Your Audience CareWhen emotions are tied to ideas, people tend to remember them for a long time, as psychologists Michael Posner and Charles Snyder discovered. Advertisers have used this technique for years, as in emotion-laden advertisements for long-distance phone service showing calls between separated family members. Emotions, however, are powerful medicine—they can work to your advantage or your disadvantage.

For example, in representing rape victims, Petty has found that jury emotions can work for and against clients. She explains, "A jury who is furious enough to send a message is more likely to find liability and punish with a large award. I convinced a jury to award $50 million against a rapist because jurists were [so] offended at what he had done. I portrayed the client as a sympathetic person, not a victim, because jurors don't like victims." She recalls another case where the client acted like a victim and that alienated the jury, who then gave her client an unfavorable verdict.

6. The Zone of Credibility Affects Listeners' BeliefsArguments that are remembered but are not believed are useless. The successful lawyer must persuade an audience that he or she is right. Or, if the judge or jury is already with you, you need to defend opinions from attack by the opponent. In your arguments, the "zone of credibility" is like a bubble around a central core that defines what your subject actually believes. The contents of the bubble around the core encompass arguments that your subject is willing to accept, even though they don't completely square with his or her beliefs. If you argue within this zone, your subject will imagine that your arguments are closer to his or her core beliefs than they actually are.

On the other hand, if your argument lies outside this zone of credibility, your subject will perceive that argument as much farther away from his or her beliefs than it actually is. This is the "boomerang" effect described by psychologist Carl Hovland and his colleagues.

If your argument gets boomeranged, your subject will reject that argument and you will lose credibility. If this happens several times, you will be perceived as an unreliable source of information-and even your correct arguments will be rejected and not recalled or believed. The keys to making the zone of credibility work for you: Don't exaggerate, be sensitive to your audience's beliefs, and watch the audience carefully for any signs of skepticism.

7. Listeners Want Freedom of ChoiceWhat should you do if you're trying to change the attitude of an unsympathetic audience? Using extreme statements that attempt to force the audience to believe only one way will most likely backfire and may turn a significant portion of your audience in the opposite direction, handing them over to your opponent, according to psychologists Stephen Worchel and Jack Brehm. Anyone who has raised teenagers has firsthand experience with this phenomenon. Giving an absolute "no" to a teenager often brings resistance and adoption of exactly the unwanted behavior. Psychologists theorize that this is because individuals feel their freedom is restricted, as when Coca-Cola abruptly replaced its traditional formula with New Coke, causing consumer outrage.

To effectively change an attitude, present your audience with both sides of the argument, emphasizing your viewpoint with some weakening of the other side's view. Avoid insisting that only one conclusion can be reached because restricting your audience's freedom of choice could lead it to adopt the opposite point of view. Even in an adversarial situation such as during negotiation, in arbitration or in a courtroom, acknowledge that the other side's arguments may have some validity.

Stewart has seen witnesses, especially expert witnesses, fall into the trap of trying to compel an audience to accept one extreme idea, only to find that they have antagonized the audience. According to Stewart, "Many professional witnesses—psychologists—make that mistake by pointing out the bad things [about] one spouse and the good things [about] the other spouse. They lose their credibility." On the other hand, the expert who presents both sides, allowing the audience some discretion, is usually perceived as fair and believable and does not alienate an audience.Stewart recalls a psychological double-whammy he used to torpedo a rising-star psychologist who was an expert witness in a custody case. Having done some pretrial reconnaissance, Stewart knew this expert typically explained to juries that, although she was hired and paid by one side, her decision would be "fair" to both sides because she was a professional. So, in a general way during voir dire, Stewart compared protestations of "being fair" to an expression of "trust me" by a panther licking its paw.

When the psychologist came into the courtroom and began explaining her evaluation process, and how her conclusions were always both professional and "fair," the members of the jury broke out laughing. They were successfully inoculated and did not want to be told what to believe.

Don't Let the Gold Go UnminedThese are only a few of the many psychological principles that lawyers can use to be more effective in the courtroom, in negotiations and in writings. These principles illustrate how the law can profit from a careful, practical look at the rich trove of research findings from psychology. A clearer understanding of how listeners absorb, process and react to information will help lawyers refine their persuasive techniques, build successful careers and win more cases.

Robert Leeper, "A Study of a Neglected Portion of the Field of Learning: The Development of Sensory Organization." Journal of Genetic Psychology, 46: 41 (1935).

William J. McGuire and Demetrios Papageorgis, "The Relative Efficacy of Various Types of Prior Belief-Defense in Producing Immunity Against Persuasion." Journal of Abnormal and Social Psychology, 62: 327 (1961).